This invention relates to water-soluble, thermally curable, cationic polyethers and to their use as additives in the manufacture of paper and other fibrous materials.
It is conventional to improve properties of paper such as wet strength, dry strength, etc. by adding certain polymers bearing quaternary ammonium salt groups. For example, U.S. Pat. No. 2,926,116 to Keim employs water-soluble, alkaline curable resins made by reacting epichlorohydrin with polyamides containing secondary amino groups. It is also known, e.g., U.S. Pat. No. 3,700,623 to Keim, to quaternize polymers of diallylamine with epichlorohydrin and then employ the resulting quaternized polymer as wet strength additives in the manufacture of paper. In the manufacture of most paper, it is desired to improve both wet strength and dry strength of the paper. In order to achieve improvement of both properties, molecular weight of the polymeric additive must be carefully controlled. Unfortunately, in the manufacture of aforementioned conventional polymeric additives, such control over molecular weight is very difficult to achieve.
In addition, many of the conventional wet strength additives are not brokable, thus recycling of scrap or waste paper that has been treated with these agents is severely restricted.
In view of the foregoing difficulties in the manufacture of wet and dry strength additives for paper, it would be highly desirable to provide a wet and dry strength additive for paper which is easier to prepare and has better properties than those of the prior art.